def test_kv_with_no_charge():
from random import seed
seed(0)
from pyrticle.units import SIUnitsWithNaturalConstants
units = SIUnitsWithNaturalConstants()
# discretization setup ----------------------------------------------------
from hedge.mesh import make_cylinder_mesh
from hedge.backends import guess_run_context
rcon = guess_run_context([])
tube_length = 100 * units.MM
mesh = make_cylinder_mesh(radius=25 * units.MM,
height=tube_length,
periodic=True)
discr = rcon.make_discretization(mesh, order=3)
dt = discr.dt_factor(units.VACUUM_LIGHT_SPEED()) / 2
final_time = 1 * units.M / units.VACUUM_LIGHT_SPEED()
nsteps = int(final_time / dt) + 1
dt = final_time / nsteps
# particles setup ---------------------------------------------------------
from pyrticle.cloud import PicMethod
from pyrticle.deposition.shape import ShapeFunctionDepositor
from pyrticle.pusher import MonomialParticlePusher
method = PicMethod(discr, units, ShapeFunctionDepositor(),
MonomialParticlePusher(), 3, 3)
nparticles = 10000
cloud_charge = 1e-9 * units.C
electrons_per_particle = cloud_charge / nparticles / units.EL_CHARGE
el_energy = 5.2e6 * units.EV
gamma = el_energy / units.EL_REST_ENERGY()
beta = (1 - 1 / gamma**2)**0.5
from pyrticle.distribution import KVZIntervalBeam
beam = KVZIntervalBeam(units,
total_charge=0,
p_charge=0,
p_mass=electrons_per_particle * units.EL_MASS,
radii=2 * [2.5 * units.MM],
emittances=2 * [5 * units.MM * units.MRAD],
z_length=5 * units.MM,
z_pos=10 * units.MM,
beta=beta)
state = method.make_state()
method.add_particles(state, beam.generate_particles(), nparticles)
# diagnostics setup -------------------------------------------------------
from pytools.log import LogManager
from pyrticle.log import add_beam_quantities, StateObserver
observer = StateObserver(method, None)
logmgr = LogManager(mode="w")
add_beam_quantities(logmgr, observer, axis=0, beam_axis=2)
from pyrticle.distribution import KVPredictedRadius
logmgr.add_quantity(
KVPredictedRadius(dt,
beam_v=beta * units.VACUUM_LIGHT_SPEED(),
predictor=beam.get_rms_predictor(axis=0),
suffix="x_rms"))
logmgr.add_quantity(
KVPredictedRadius(dt,
beam_v=beta * units.VACUUM_LIGHT_SPEED(),
predictor=beam.get_total_predictor(axis=0),
suffix="x_total"))
# timestep loop -----------------------------------------------------------
vel = method.velocities(state)
from hedge.tools import join_fields
def rhs(t, y):
return join_fields([
vel,
0 * vel,
0, # drecon
])
from hedge.timestep.runge_kutta import LSRK4TimeStepper
stepper = LSRK4TimeStepper()
t = 0
from pyrticle.cloud import TimesteppablePicState
ts_state = TimesteppablePicState(method, state)
for step in xrange(nsteps):
observer.set_fields_and_state(None, ts_state.state)
logmgr.tick()
ts_state = stepper(ts_state, t, dt, rhs)
method.upkeep(ts_state.state)
t += dt
logmgr.tick()
_, _, err_table = logmgr.get_expr_dataset(
"(rx_rms-rx_rms_theory)/rx_rms_theory")
rel_max_rms_error = max(err for step, err in err_table)
assert rel_max_rms_error < 0.01
def test_kv_with_no_charge():
from random import seed
seed(0)
from pyrticle.units import SIUnitsWithNaturalConstants
units = SIUnitsWithNaturalConstants()
# discretization setup ----------------------------------------------------
from hedge.mesh import make_cylinder_mesh
from hedge.backends import guess_run_context
rcon = guess_run_context([])
tube_length = 100*units.MM
mesh = make_cylinder_mesh(radius=25*units.MM, height=tube_length, periodic=True)
discr = rcon.make_discretization(mesh, order=3)
dt = discr.dt_factor(units.VACUUM_LIGHT_SPEED()) / 2
final_time = 1*units.M/units.VACUUM_LIGHT_SPEED()
nsteps = int(final_time/dt)+1
dt = final_time/nsteps
# particles setup ---------------------------------------------------------
from pyrticle.cloud import PicMethod
from pyrticle.deposition.shape import ShapeFunctionDepositor
from pyrticle.pusher import MonomialParticlePusher
method = PicMethod(discr, units,
ShapeFunctionDepositor(),
MonomialParticlePusher(),
3, 3)
nparticles = 10000
cloud_charge = 1e-9 * units.C
electrons_per_particle = cloud_charge/nparticles/units.EL_CHARGE
el_energy = 5.2e6 * units.EV
gamma = el_energy/units.EL_REST_ENERGY()
beta = (1-1/gamma**2)**0.5
from pyrticle.distribution import KVZIntervalBeam
beam = KVZIntervalBeam(units,
total_charge=0,
p_charge=0,
p_mass=electrons_per_particle*units.EL_MASS,
radii=2*[2.5*units.MM],
emittances=2*[5 * units.MM * units.MRAD],
z_length=5*units.MM,
z_pos=10*units.MM,
beta=beta)
state = method.make_state()
method.add_particles(state, beam.generate_particles(), nparticles)
# diagnostics setup -------------------------------------------------------
from pytools.log import LogManager
from pyrticle.log import add_beam_quantities, StateObserver
observer = StateObserver(method, None)
logmgr = LogManager(mode="w")
add_beam_quantities(logmgr, observer, axis=0, beam_axis=2)
from pyrticle.distribution import KVPredictedRadius
logmgr.add_quantity(KVPredictedRadius(dt,
beam_v=beta*units.VACUUM_LIGHT_SPEED(),
predictor=beam.get_rms_predictor(axis=0),
suffix="x_rms"))
logmgr.add_quantity(KVPredictedRadius(dt,
beam_v=beta*units.VACUUM_LIGHT_SPEED(),
predictor=beam.get_total_predictor(axis=0),
suffix="x_total"))
# timestep loop -----------------------------------------------------------
vel = method.velocities(state)
from hedge.tools import join_fields
def rhs(t, y):
return join_fields([
vel,
0*vel,
0, # drecon
])
from hedge.timestep.runge_kutta import LSRK4TimeStepper
stepper = LSRK4TimeStepper()
t = 0
from pyrticle.cloud import TimesteppablePicState
ts_state = TimesteppablePicState(method, state)
for step in xrange(nsteps):
observer.set_fields_and_state(None, ts_state.state)
logmgr.tick()
ts_state = stepper(ts_state, t, dt, rhs)
method.upkeep(ts_state.state)
t += dt
logmgr.tick()
_, _, err_table = logmgr.get_expr_dataset("(rx_rms-rx_rms_theory)/rx_rms_theory")
rel_max_rms_error = max(err for step, err in err_table)
assert rel_max_rms_error < 0.01
